This invention concerns apparatus for indexing or conveying work to be operated upon in various ways, and deals more specifically with apparatus having a pair of parallel spaced transfer bars for transferring work through a series of processing stations as, for example, in a three-dimensional transfer press.
As is well known, the three-dimensional transfer press is a streamlined machine incorporating a series of press stations for continuously processing flat work into a variety of panel products such as those used for roofing, flooring, and doors. Extending horizontally throughout the press, the aforesaid pair of transfer bars are reciprocated longitudinally and further moved up and down and toward and away from each other. By the repetition of these motions in a prescribed sequence the transfer bars act to grip, lift, and transport successive workpieces from one press station to the next.
The conventional mechanisms for such longitudinal, transverse, and vertical motions of the transfer bars have all been driven from the transfer press itself via gear trains, linkage systems, etc. Consequently, in order to provide several different transfer bar strokes in each of the longitudinal, transverse, and vertical directions, as many cams or equivalent machine elements have had to be incorporated in each mechanism, making it complex in construction and bulky in size.
With use of the cams or the like, moreover, the transfer bar strokes are not infinitely variable, but only stepwise. Nor are the transfer bar positions at the starts and ends of their longitudinal, transverse, and vertical movements easily readjustable. This is highly inconvenient as the transfer press is intended to handle workpieces of various shapes and sizes for the fabrication of correspondingly varied pressings.
An additional problem of the prior art arises from the fact that the mechanisms fof the longitudinal, transverse, and vertical motions of the transfer bars have all been mechanically and operationally interrelated. This has made it difficult to service the mechanisms individually, and to split up the transfer bars into required numbers of segments for the change of press dies as well as of work gripping fingers on the transfer bars.